"If another powder mill blows up," chuckled Tom, "you won't need to be called. You'll be out here on the jump." Dave, Dan and Harry thereupon turned in. Knowing that others were on watch the trio in the tent were all sound asleep within five minutes. Only the sighing of the wind through the trees, the occasional splash of a leaping fish in the lake, and the subdued, musical hum of tiny night insects came to the ears of Dick and his fellow watchers. Greg was soon yawning. Tom, for want of something better to do, began describing all over again the strange apparition he and Dalzell had seen that afternoon. Greg, finding the "creeps" in Tom's narration to be stronger than the interest, shivered and withdrew to a spot beyond the reach of Tom's whispers. Not long after Greg, his back propped against a tree trunk, was sound asleep. Tom liked to talk. Prescott was a good listener, putting in a question now and then. So at least another hour passed. Then----- Boo-oom! That crash was so close at hand that it seemed as though the earth must open. Tom's first startled glance was at the sky. Then, with a whisking sound, several fragments of something passed over their heads. "We're being bombarded?" gasped Tom inquiringly. "This is getting too noisy to be interesting," protested Greg, waking and leaping over to the place where his chums stood. "I thought you fellows were going to put a stop to that racket!" complained Darry from the tent. Dick Prescott's whole thought and effort had been centered on the task of placing the location of that latest explosion. "You fellows look after the camp," Dick called in a low voice to those in the tent. "Come on, Tom and Greg!" His two chums hurried to overtake him as the young leader rushed off in the darkness. Prescott was traveling up the slope in a direction that ran in an oblique line from the lake front. "Are you sure it was just exactly in this direction?" whispered Reade, as he reached Dick's side. "In this direction as nearly as I could judge," Dick affirmed. For some moments they traveled onward. Then they halted to listen. "I don't know whether I'm any good at judging distances," Dick whispered, "but it seemed to me that whatever exploded was not much more than three hundred yards from camp." "About that distance, I should say," Tom agreed. "Then we've gone about as far as the place of the explosion. Suppose we keep very quiet and listen." "Ugh!" grunted Greg. "I hope the earth doesn't blow up under our feet." "Go back to camp, if you're nervous," smiled Dick, but Greg remained where he was. "I'm going out a little way and prowl," whispered Dick, pointing in the direction he had chosen. "Tom, why don't you travel in about the opposite direction?" Reade nodded. "Where shall I go?" asked Greg. "You had better remain right here," Prescott whispered. "If you should hear either of us yell for help then you could start in the direction of the sound."